Hadrian's Wall is believed to have been constructed between 122 and 127 AD. It replaced an older line of roads and fortifications called the Stanegate that was built by Agricola to control the territory and the frontier. Hadrian found the old system inadequate to control the frontier, and at his order the Wall was constructed north of the Stanegate, and after it was in service forts were built to the south of the Wall. Some of these, such as the one at Chesterholm (Vindolanda) were adapted from the older Stanegate fortifications and thus are some distance south of the actual Wall.